Article excerpt

Background

Stillbirth is a major cause of pregnancy loss, particularly in poor countries. In sub-Saharan Africa and southern Asia, some 5% of pregnancies end in this way, whereas in Europe and North America the proportion is generally less than 1%. In the latter regions, much is known about such causal factors as hypertension, obesity, eclampsia, advancing age and smoking. (1) In poor countries, there has been much less research, and the main concern has been for early pregnancy, inadequate nutrition, endemic malaria, stature and poor physique, all or any of which may have an important role. (2) Our immediate need is to determine whether, in Bangladesh, the widespread arsenic contamination of water in hand-pump tubewells is potentially hazardous for pregnant women. Though this question could be approached ecologically with the considerable information on the geographical distribution of arsenic in wells based on the National Hydrochemical Survey, together with stillbirth rates by district, the possibility of confounding by socioeconomic factors and health status also has to be excluded.

Serious natural contamination of water with arsenic and other minerals in village hand-pump tubewells in Bangladesh and West Bengal is well documented, (3) as are the skin lesions that resuh. (4-10) A wide range of other types of disease, mainly from occupational exposure to inhaled arsenic, have included internal cancers of the lung and other organs and various chronic inflammatory diseases, but effects on the outcome of pregnancy have not been clearly identified. (11) However, the longstanding use of arsenic as an abortifacient, together with results from animal studies, (12) suggests that such effects are not improbable, and there is evidence that arsenic concentrations in the urine of pregnant women reflect their level of chronic exposure. (13) In 2001, a study in Bangladesh of pregnancy outcomes in 192 women, half in a village with high arsenic levels, found 17 stillbirths compared with seven in a similar village with low levels. (14) A more recent study of 533 women drawn randomly from 74 villages, mostly with high arsenic concentrations (mean 277 [micro]g/1; median 116 [micro]g/1) showed evidence of increased risk of fetal and infant death. (15) This study, although based on only 48 stillbirths, allowed analysis of reproductive history and educational status by logistic regression. (15) A study of 202 pregnant women identified from a cross-sectional survey of almost 8000 people in 21 West Bengal villages found evidence of a significant increase in stillbirth at concentrations of [greater than or equal to] 200 [micro]g/l. (16) However, a study of 2006 pregnant women in three selected upazillas (subdistricts) found no association with stillbirth. (17)

There is still a requirement for evidence based on reliable data in well-supervised large populations exposed to arsenic over a range of concentrations. These requirements are largely met by Gonoshasthaya Kendra (GK; the People's Health Centre), a large, well established nongovernmental organization, which currently provides comprehensive health care for the entire population of about one million in some 600 villages, spread across four of Bangladesh's six main divisions. Most of the villages in the GK network are located in districts where the average arsenic concentration in hand-pump tubewells is low (< 50 [micro]g/l), but many are in areas with average concentrations well above that; in addition, there is enormous variation between and within villages. Cross-sectional and case-referent surveys of skin lesions in a large sample of GK villages have shown an average prevalence of 0.37% at concentrations < 5 [micro]g/l, rising to 6.84% at > 50 [micro]g/1. (18,19)

As GK has always maintained a complete census of residents in its villages and has systematically recorded all pregnancies with outcome, together with some 30 health and socioeconomic variables, these data should provide useful information on the epidemiology of stillbirth in this population of over a million residents in rural Bangladesh against which any additional effect of arsenic can be assessed. …